The invention proposes a multidirectional actuator that comprises a tilting actuation member and means for producing a force for returning the actuation member.
There are numerous devices called joysticks that are used in various applications such as gaming joysticks or joysticks for one or more accessories of a motor vehicle, such as for example an agricultural machine or a worksite machine.
Such a joystick is usually mounted so as to articulate relative to a fixed support, and the user grasps the joystick with the hand to make it pivot and/or tilt relative to its support.
However, merely the pivoting and/or tilting movements of the joystick relative to its support may prove insufficient to control an accessory of an agricultural machine.
That is why it has been proposed to add a certain number of actuators to the joystick.
The joystick then supports for example buttons each of which makes it possible to control an additional function of the accessory of the agricultural machine and it supports actuators of the multidirectional type.
It is in particular desirable that the user is able to manipulate such a multidirectional actuator with a single finger, for example his thumb, the actuator being installed on a main front face of the joystick.
Document U.S. Pat. No. 6,266,046 describes such a multidirectional actuator that comprises a bottom support attached to the structure of the joystick and an actuation member that is mounted so as to tilt relative to the support towards several actuation positions.
Each of the actuation positions of the actuation member relative to the support is characterized by the angle of inclination of the main axis of the actuation member relative to the vertical axis of the support, and by the angular position of the actuation member about the vertical axis of the support.
The actuator comprises means of measuring the value of the angle of inclination of the main axis of the actuation member relative to the vertical axis of the support, and of measuring the angular position of the actuation member about the vertical axis of the support.
The measurement means are connected to an electronic device that is capable of determining the actuation position of the actuation member according to the angle of inclination of the main axis of the actuation member, and according to the angular position of the actuation member about the vertical axis of the support that have been measured.
According to this document, the measurement means comprise a movable magnet that is attached to the actuation member, and Hall effect sensors that are attached to the support.
The actuator also comprises means of returning the actuation member to a central rest position.
When the user manipulates the joystick or the actuator to control the accessory of the machine, he mostly looks at the accessory and he only rarely looks at the joystick and the actuator.
Thus, the user perceives the actuation position of the actuation member relative to the support essentially by the sensations produced by the force returning the actuation member to its rest position.
The return force is produced by an elastic element, here a spring, that is mounted compressed between the support and an intermediate button, so that the greater the angle of inclination of the actuation member relative to the support, the more the spring is compressed and consequently the greater the return force.
However, the return force does not vary according to the angular position of the actuation member about the vertical axis of the support.
Thus, for example when the user simultaneously inclines the joystick and the actuation member, he does not correctly perceive the angular position of the actuation member relative to the joystick.